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Personal Cloning Therapy Advances; Trial in Cow Offers Hope for Humans

Posted on: Thursday, 30 June 2005, 18:01 CDT

Therapeutic cloning, an experimental technique that could one day allow patients to be treated with their own rejuvenated cells, moved one step closer to reality as researchers announced a successful trial in cows Wednesday.

The experiment involved creating an embryo that was a genetic clone of the "parent" cow. Researchers then removed stem cells from the cloned embryo and administered those cells back to the original "parent" cow. As long as six months later, the cloned cells were still detectable in the cow's bloodstream and bone marrow.

From the blood and marrow, stem cells can migrate to organs such as the heart and liver, where the stem cells can replace older, worn- out cells. Stem cells are immature cells that can differentiate, or turn into, any mature cell a bone, muscle or liver cell, for example. Scientists are studying stem cells as a potential treatment for diseases, hoping that the stem cells will replace injured or unhealthy cells.

"This could be a whole new paradigm," said Robert Lanza, medical director at Advanced Cell Technology in Worcester, Mass., and lead author of the study that appears in the June issue of Cloning and Stem Cells. "This technology could take an old, decrepit cell and return it to its youthful state."

Therapeutic cloning refers only to the creation of cells in a lab dish. Because the cells are never implanted in a womb, no human fetus ever forms, nor are organs created. Researchers harvest stem cells that they would later administer back to the patient.

Typically, when foreign cells are introduced into a person's bloodstream, the body's immune system mounts a defense. The advantage of cloned stem cells is that they're genetically identical to the host's cells, so the body does not reject them.

"If you want to treat someone with pneumonia, you don't want to give them a treatment that will lower their white blood cell count," said Lanza, referring to the blood cells that seek out and destroy foreign cells. "But with therapeutic cloning, you don't need to suppress the immune system."

Other scientists called Lanza's findings interesting, but not groundbreaking.

"This sort of thing has already been done in a mouse, so the proof of principle was already there," said Timothy Kamp, associate professor of medicine at the University of Wisconsin Medical School in Madison. "Still, it's a step forward because it's closer to humans."

A cell is cloned by transferring its genetic material into an egg cell with its genetic material removed. As the cell divides, each arising stem cell will share genetic material identical to the original cell. Those stem cells can then be administered, in theory, back to the patient.

In May a team of South Korean scientists was the first to create a line of cloned human stem cells. Still, researchers caution that a similar treatment in humans is still at least five years away.

A key next step is to determine how to administer the cells, whether by injecting them directly into a specific organ, or simply injecting them into the bloodstream to circulate and accumulate where they are most needed.

Either way, scientists must first be able to strictly control how and when stem cells differentiate, said John Lough, a stem cell researcher at the Medical College of Wisconsin.

"If you want to turn stem cells into heart tissue, you might be 80 percent effective, but that other 20 percent have the potential to become tumors," Lough said. "We'd have to be up at 100 percent effectiveness before we could use this on humans."

And getting to 100% effectiveness won't be easy, said Gary Lyons, professor of anatomy at UW Medical School.

"If a person has had a heart attack, the environment in which you're injecting the cells is a very hostile environment, generally leading to the death of most of the cells you inject," he said.

The latest research on cloning comes amid debate on state legislation that would ban reproductive and therapeutic cloning. The Assembly passed the bill last week and the Senate is in line to take up an identical bill. Researchers are split on how the legislation would affect state research.

"I think it sends a pretty strong message to both researchers on campus as well as the biotech community that Wisconsin is not a friendly place for stem cell research," Kamp said. "You don't always want to worry about your research being outlawed next week."

Lyons said as long as researchers adhere to guidelines, this bill is redundant.

"At UW-Madison, we work within the federal guidelines, and we don't create new stem cell lines, so I think we'd be OK," he said.

Susan Armacost of Wisconsin Right to Life said her organization has no position on animal cloning, but opposes cloning human embryos.

"Manufacturing them for research is wrong," she said.

Copyright 2005, Journal Sentinel Inc. All rights reserved. (Note: This notice does not apply to those news items already copyrighted and received through wire services or other media.)

Source: Milwaukee Journal Sentinel

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